When you erase your Apple Watch

When you erase all content and settings, it completely erases your device, including any cards you added for Apple Pay and any photos, contacts, music, or apps. It also turns off iCloud, iMessage, FaceTime, Game Center, and other services. Your content won't be deleted from iCloud when you erase your device.

Before you buy a watch from a third-party

Before you buy an Apple Watch from someone other than Apple or an authorized Apple reseller, make sure that the device is no longer linked to the previous owner’s account.

Make sure that the previous owner removed Activation Lock from the watch and that the watch has been erased. They must unpair the watch and remove Activation Lock by entering their Apple ID password, so you can use the watch.

If you see the passcode lock screen or the Home screen, the device needs to be erased.

If you can, try to pair the watch with your iPhone. If you're asked to enter the previous owner's Apple ID password during setup, then Activation Lock is still on.